Lynn,
the dyno sheet looks like a standard dyno run where the engine was
run
from idle to WOT. In this case, it looks like the carb started to
be
a restriction between 5500 and 6000 RPM, due to the drop in manifold
pressure.
The question I have is if anyone has made dyno runs using
the engine as
we're more likely to use it in an airplane. Has anyone
made a run at
WOT, and then use the mixture control to vary power?
At 5500 RPM, the
sheet shows 174 Hp and a BSFC of .55 lb/Hphr. At
6500 RPM, the Hp goes
to 195 and the BSFC is back at .55. The
airflow is obviously increased,
because the Mp dropped. What would
happen to the BSFC if the airflow
for 6500 RPM is maintained, but the fuel
is cut from the 108 lb/hr to
the 98 lb/hr used at 5500 RPM?
I may
(most likely?) just be completely confused about how it all works,
but I
know that Ed has mentioned that he controls power with mixture;
however, I've never seen a dyno sheet that explicitly stated that it was
a power curve generated by varying mixture at WOT.
It seems like the turbo is a bit small and pressure is dropping off early.
You need fuel to help cool the engine and help the turbo. So this was not
the last pass before the race. You can have just about any amount of HP you want
by just adding boost.
The cooling load may be high and the cooling system my prove
inadequate.
It seemed to me that this was not a true outcome sheet, but were just
playing with the engine. It is turbo charged and Clayton Cunningham is/was a
world famous builder of piston and rotary engines.
I would expect to see A/F at all RPM. And EGT both pipes. Injection was
legal in IMSA so no jetting data of course. Injector size or "Pop" pressure
would have been nice.
Oil temps? Ignition advance? Spark plug brand and gap?
It is not typical to have an unidentified engine on the dyno. Bill
Jongbloed was a wheel manufacturer. Was this JB001?
The engine is not being pressed very hard at all.
Apex seals are stock? Carbon? Ceramic?
Water temp is of no value because you have a reserve tank of cold water
that keeps the temps stable for test repeatability.
The un-labled sheet may be the same engine, or, a similar engine. I think
this was just the start of an engine program.
The idea that this or any engine was expected to last only 6 hours, is
suspect. True it will be down a few HP after 6 hours of runs up to 9,300 RPM,
but it might also last many race seasons without any further maintenance.
Daryl Drummond wanted our engines back after 8 hours to change apex and
side seals.
He never saw them again. We just did not have the money to do it. I
changed the ports so that side seals would not wear off the corners, and
the engines stayed tight and strong for two years at a time.
Lynn E. Hanover